Let's put it this way: Myst came out in 1993, which coincides with an era in which I was very actively involved in the PC game business at a technical level. If you were playing PC games back then, you were probably running some of my code.

So yes, if we're talking "Myst class" relative to the 1993 release, I'm very confident that I could vibe-wrangle something just like it in a week, using only open models that were released within the last month or so. When I say "It's just too soon," I mean that the capabilities exist now, but they are new enough that no one has had time to do anything interesting with them. And cloning a 1993 game is not especially interesting, at least not to me.

Obviously the Myst franchise hasn't stood still since then. I don't know anything about the newer releases, so I'd have to do some hedging there. You would rightfully complain that any new Myst game that someone hacks in a week would not be competitive with the SotA. But it could certainly stand up to the original.